Program name: FileZilla Client version 3.29.0
Link to installer: https://download.filezilla-project.org/client/FileZilla_3.29.0_win64-setup_bundled.exe
Link to Unchecky Info Tool report: https://unchecky.com/info_tool?1511280615_ovwgG6g2Q-nA0HxJ
The offer is for Avast Antivirus. While security software is important, most computers now come with security software installed, (Windows defender is an example), or people have chosen their own preferred brand of security software.
Installing more than one antivirus solution can lead to crashes, system halts, and a multitude of other system problems. I believe that deselecting this offer by default is wise for these reasons. During install, users can easily see the offer, and can choose to override unchecky's deselect, and install the offer anyway.
I personally use Comodo, so installing Avast along with it wouldn't be wise.
Customer support service by UserEcho